/*
 * Copyright (c) 2010, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.max.vm.ext.vma.store;

import com.oracle.max.vm.ext.vma.store.txt.*;


public abstract class RepeatIdHandler {
    protected static final String NO_REPEATS_PROPERTY = "max.vma.norepeatids";
    protected static boolean doRepeats;

    public static RepeatIdHandler create(boolean perThread) {
        doRepeats = System.getProperty(NO_REPEATS_PROPERTY) == null;
        if (perThread) {
            return new PerThreadRepeatIdHandler();
        } else {
            return new GlobalRepeatIdHandler();
        }
    }

    /**
     * Mutable "long" for recording last object id used by a thread.
     */
    protected static class LastId {
        long id = VMATextStoreFormat.REPEAT_ID_VALUE;
    }

    /**
     * Check if this {@code objId} is the same as the previous one.
     * Note that all traces that start with an {@code objId} must call this method!
     * @param id
     * @param threadName
     * @return {@link TextVMAdviceHandlerLog#REPEAT_ID_VALUE} for a match, {@code id} otherwise
     */
    public long checkRepeatId(long id, String threadName) {
        LastId lastId;
        if (doRepeats) {
            lastId = getLastId(threadName);
            if (lastId.id == id) {
                return VMATextStoreFormat.REPEAT_ID_VALUE;
            } else {
                lastId.id = id;
            }
        }
        return id;
    }

    protected abstract LastId getLastId(String threadName);


}
